The effect of aging on brain respiration and carbohydrate metabolism will be studied using hamsters as an animal model. Oxygen uptake and intermediates of carbohydrate metabolism will be measured in young and old animals using tissue slice techniques and electrical and chemical stimulation. The effect of phenobarbital, altered pH and elevated temperature will also be studied. Demonstration of altered metabolism in brains of old animals under these various conditions would help clarify clinicaly observed disorders of brain function in the elderly..